You can try Halo 4 weapon pack or COD:Ghost weapon pack since if I can remember both mods contain futuristic shotguns. I don't recall thatany futuristic shotguns still use lever system though. Also, it seems you are request certain mods so I suggest you move your topic to Mod Suggestions& Requests section.

Lever action shotguns aren't really futuristic so it would be hard to find one. The most I can do is point you towards a good lever action shotgun. http://www.nexusmods.com/newvegas/mods/38216/?

It's a unique Lever Action Shotgun. Designed to be like Ranger version of the shotgun like how the Ranger Sequoia is variant of a revolver. It isn't really "futuristic", but neither is a lever action shotgun. Hope it helps.